well, if your chamois isn't too thin, another potential problem could be saddle angle or seatpost height. a lot of girls i know like to have the post a little high to get more leg power, but that will definatly cause some pain, so mebbe try to do a couple runs 1/2 an inch shorter. also, you could tilt the nose of your saddle down just a smidge... i ride for 6hrs a day on a super hard road saddle and never need to use any kind of chamois cream....
good luck